. Bulletin of the British Museum (Natural History), Geology. Ptr. Ptr, infc Fig. 14. Cheirolepis trailli Agassiz. (a) Reconstruction of skull roof. Mainly from 425. (b) Reconstruction of snout. The snout region is never very satisfactorily preserved and consequently the interpretation of it is open to question, also there appears to be some variability in the bone arrangement from specimen to specimen. My own interpretation of the snout region is given in Text-fig. 14B, and I believe that there is a single paired ossification ventro-anteriorly, the rostro-premax
. Bulletin of the British Museum (Natural History), Geology. Ptr. Ptr, infc Fig. 14. Cheirolepis trailli Agassiz. (a) Reconstruction of skull roof. Mainly from 425. (b) Reconstruction of snout. The snout region is never very satisfactorily preserved and consequently the interpretation of it is open to question, also there appears to be some variability in the bone arrangement from specimen to specimen. My own interpretation of the snout region is given in Text-fig. 14B, and I believe that there is a single paired ossification ventro-anteriorly, the rostro-premaxillo-antorbital. Evidence of this ossification and of the nasal which lies above it can be seen on , and also on , 35778 and The nasal (, ) bears two notches, one anteriorly for the anterior nostril (nax) and the other posteriorly for the posterior nostril (na2). Dorso-posteriorly the nasal joins the supraorbital. Thus on my interpretation the snout of Cheirolepis trailli is very similar to that seen in other primitive palaeoniscoids, in particular Stegotrachelus finlayi and Tegeolepis clarki. Further, since it seems probable that the primitive actinoptery- gian snout was composed basicaUy of three bones only, the paired nasals, the paired rostro-premaxillo-antorbitals and a median postrostral (see later under discussion), Cheirolepis trailli now fits into place and is no longer an exception to the rule. As a further justification for my reconstruction of the snout region of Cheirolepis trailli, I would like to point out that I have not seen an independent rostral element below the parasemionotid level of Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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